While I do not recommend anyone do this, I ran a test at about 170' where 1 HR20 tuner (took off the second tuner) drove an AT9 thru a 6x8 multiswitch which was wired in parallel with another multiswitch. Total cable length was about 170' IIRC. Note, all other ports on the two switches were turned off or unplugged. Flipped thru channels a bit slowly as I switched between LNBs, but it seemed to work fine.
The cable was all solid copper core, about a year in place, no splices except at wall jacks, etc.
Cheers,
Tom